Miniature thin-film bandpass filter

A thin-film bandpass filter comprising:

• at least two thin-film layers;
• a first resonant circuit including a first inductor;
• and
• a second resonant circuit including a second inductor;
• wherein the first inductor comprises a coil having a clockwise rotation positioned in two or more of the at least two thin-film layers;
• wherein the second inductor comprises a coil having a counter-clockwise rotation positioned in two or more of the at least two thin-film layers;
• and
• wherein the first inductor is coupled to the second inductor in at least two of the at least two thin-film layers when the bandpass filter is energized.

A thin-film bandpass filter comprising:

• at least two thin-film layers, including a first thin-film layer and a second thin-film layer;
• a first inductor and a first capacitor forming a first resonant circuit;
• a second inductor and a second capacitor forming a second resonant circuit;
• an input capacitor connected between the first resonant circuit and an input terminal;
• an output capacitor connected between the second resonant circuit and an output terminal;
• and
• a coupling capacitor connected between the input terminal and the output terminal;
• wherein the first inductor is comprised of a counter-clockwise turning coil starting at the first thin-film layer and finishing at the second thin-film layer, the first inductor being connected to the input capacitor and the first capacitor at the first thin-film layer and being connected to ground at the second thin-film layer;
• wherein the second inductor is comprised of a clockwise turning coil starting at the first thin-film layer and finishing at the second thin-film layer, the second inductor being connected to the output capacitor and the second capacitor at the first thin-film layer and being connected to ground at the second thin-film layer;
• and
• wherein at least a portion of the coils of the first and second inductors are coupled in either the first thin-film layer or the second thin-film layer.

A thin-film bandpass filter comprising:

• at least two thin-film layers, including a first thin-film layer and a second thin-film layer;
• a first inductor and a first capacitor forming a first resonant circuit;
• a second inductor and a second capacitor forming a second resonant circuit;
• an input capacitor connected between the first resonant circuit and an input terminal;
• an output capacitor connected between the second resonant circuit and an output terminal;
• and
• a coupling capacitor connected between the input terminal and the output terminal;
• wherein the first inductor is comprised of a clockwise turning coil starting at the first thin-film layer and finishing at the second thin-film layer, the first inductor being connected to the input capacitor and the first capacitor at the first thin-film layer and being connected to ground at the second thin-film layer;
• wherein the second inductor is comprised of a counter-clockwise turning coil starting at the first thin-film layer and finishing at the second thin-film layer, the second inductor being connected to the output capacitor and the second capacitor at the first thin-film layer and being connected to ground at the second thin-film layer;
• and
• wherein at least a portion of the coils of the first and second inductors are coupled in at least the first thin-film layer and the second thin-film layer.